Crash Course Astronomy | Dark Energy, Cosmology part 2: Crash Course Astronomy #43 | Episode 43 | PBS

The majority of the universe is made up of a currently mysterious entity that pervades space: dark energy. We don’t know exactly what it is, but we do know that dark energy accelerates the expansion of space. We think this means the Universe will expand forever, even as our view of it shrinks while space expands faster all the time.